Decades-old question surrounding the start of the tree of life could finally be solved

Published

2 years ago

May 25, 2023

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A blood-belly comb jelly Lampocteis cruentiventer collected off the coast of San Diego. (Image credit: Yiming Chen/Getty Images)

After decades of debate, scientists believe they have identified the most recent ancestor of the sister to all animals via the novel use of an analytical technique. The finding settles a central question about the evolution of the entire tree of animal life.

All animal life is descended from a single common ancestor — a multicellular organism that most likely lived more than 600 million years ago. This ancestor had two offspring; one that led to the evolution of all animal life, and another that is referred to as the sister to all animals.

In the quest to identify which living animals are most closely related to this sister group, scientists have narrowed down the possibilities to two candidates: sea sponges and comb jellies (ctenophores). Conclusive evidence to support either candidate, however, has remained elusive.

Now, a new study published May 17 in the journal Nature has resolved this long-running debate with the novel use of chromosomal analysis.

The debate over the ancestors of sea sponges (left) and comb jellies (right) has been going on for decades. (Image credit: Reinhard Dirscherl/RibeirodosSantos/Getty Images)

The solution came while Darrin T Schultz, lead author and current postdoctoral researcher at the University of Vienna, and a multi-institutional team were sequencing the genomes (the complete set of genetic information) of comb jellies and their close relatives to understand more about their evolution.

Related: Alien-like comb jellies have a nervous system like nothing ever seen before

Rather than comparing individual genes, the team looked at their positions on chromosomes across species. While changes to DNA occur over the course of evolution, genes tend to remain on the same chromosome. On rare occasions of fusion and mixing, genes transfer from one chromosome to another in an irreversible process. Schultz compares this to shuffling a deck of cards. If you have two decks of cards and you shuffle them, they become mixed. “Once mixed, you can’t unmix it in the way it was before, the probability of that is almost impossible,” Schultz told Live Science.

In other words, once a gene has moved from one chromosome to another, there is almost zero chance of it appearing in its original position again further down the evolutionary line. By looking at the large-scale movement of groups of genes across animal groups, Schultz and the team were able to gain important insights into the family tree of these animals.

The team found 14 groups of genes that appeared on separate chromosomes in comb jellies and their single-celled, non-animal relatives. Interestingly, in sponges and all other animals, these genes had rearranged into seven groups.

Given that the DNA of the comb jellies holds the gene groups in their original position (prior to rearranging into the seven groups) it is indicative that they are descendants of the sister group that broke from the animal family tree, before the mixing occurred. RELATED STORIES—What’s the weirdest sea creature ever discovered?

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Further, the gene location rearrangements that were common to both sponges and all other animals suggest a shared ancestor from which these rearrangements were inherited. The findings, therefore, resolve the controversial question over the lineage of the entire animal tree of life.

Since the ancestors of comb jellies and sponges branched off from the family tree, their modern descendants have continued to evolve, so we cannot use this information to indicate what the first animals exactly looked like. However, scientists believe there is significant value in studying these modern animals in light of this new information about their lineage. “If we understand how all animals are related to one another, it helps us understand how animals evolved the things that make them animals,” Schultz said.

Entertainment

MasterChef presenter John Torode sacked

Published

3 hours ago

July 15, 2025

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MasterChef presenter John Torode will no longer work on the show after an allegation he used an “extremely offensive racist term” was upheld, the BBC has said.

His co-host Gregg Wallace was also sacked last week after claims of inappropriate behaviour.

On Monday, Torode said an allegation he used racist language was upheld in a report into the behaviour of Wallace. The report found more than half of 83 allegations against Wallace were substantiated.

Torode, 59, insisted he had “absolutely no recollection” of the alleged incident involving him and he “did not believe that it happened,” adding “racial language is wholly unacceptable in any environment”.

In a statement on Tuesday, a BBC spokesperson said the allegation “involves an extremely offensive racist term being used in the workplace”.

The claim was “investigated and substantiated by the independent investigation led by the law firm Lewis Silkin”, they added.

“The BBC takes this upheld finding extremely seriously,” the spokesperson said.

“We will not tolerate racist language of any kind… we told Banijay UK, the makers of MasterChef, that action must be taken.

“John Torode’s contract on MasterChef will not be renewed.”

Australian-born Torode started presenting MasterChef alongside Wallace, 60, in 2005.

A statement from Banijay UK said it “takes this matter incredibly seriously” and Lewis Silkin “substantiated an accusation of highly offensive racist language against John Torode which occurred in 2018”.

“This matter has been formally discussed with John Torode by Banijay UK, and whilst we note that John says he does not recall the incident, Lewis Silkin have upheld the very serious complaint,” the TV production company added.

“Banijay UK and the BBC are agreed that we will not renew his contract on MasterChef.”

Earlier, as the BBC released its annual report, its director-general Tim Davie addressed MasterChef’s future, saying it can survive as it is “much bigger than individuals”.

Speaking to BBC News after Torode was sacked, Mr Davie said a decision is yet to be taken over whether an unseen MasterChef series – filmed with both Wallace and Torode last year – will be aired.

“It’s a difficult one because… those amateur chefs gave a lot to take part – it means a lot, it can be an enormous break if you come through the show,” he added.

“I want to just reflect on that with the team and make a decision, and we’ll communicate that in due course.”

Mr Davie refused to say what the “seriously racist term” Torode was alleged to have used but said: “I certainly think we’ve drawn a line in the sand.”

In 2022, Torode was made an MBE in the Queen’s Birthday Honours, for services to food and charity.

Politics

Programmable regulation is the missing key to DeFi’s legal future

Published

3 hours ago

July 15, 2025

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Programmable regulation is the missing key to DeFi’s legal future

Programmable regulation could be the solution to legacy regulatory frameworks struggling to keep pace with DeFi’s rapidly evolving ecosystems. Embedding compliance in code can bring legal clarity, reduce risk and foster innovation in DeFi.

UK